Four new cyclic heptapeptides, mortiamides A-D (1-4), were obtained from a novel Mortierella sp. isolate obtained from marine sediment collected from the intertidal zone of Frobisher Bay, Nunavut, Canada. The structures of the compounds were elucidated by NMR spectroscopy and tandem mass spectrometry. The absolute configurations of the amino acids were determined using Marfey's method. Localization of l and d amino acids within each compound was ascertained by retention time comparison of the partial hydrosylate products of each compound to synthesized dipeptide standards using LC-HRMS. Compounds 1-4 did not exhibit any significant antimicrobial or cytotoxic activity.
Four new cyclic decapeptides, auyuittuqamides
A–D (1–4), were obtained from Sesquicillium
microsporum RKAG 186 obtained from marine sediment collected
from the intertidal zone of Frobisher Bay, Nunavut, Canada. The structures
of the compounds were elucidated by NMR spectroscopy and tandem mass
spectrometry. The absolute configurations of the amino acids were
determined using Marfey’s method.
Two new decalin-tetramic acid compounds, iqalisetin A (1) and iqalisetin B (2), were identified from a Tolypocladium sp. isolated from a marine sediment sample collected from Frobisher Bay, Nunavut, in Canada’s arctic. The structures of the new compounds were elucidated by NMR experiments. The relative stereochemistry of the decalin skeleton was determined by NOESY experiments and confirmed that 1 and 2 contained a trans-decalin ring system. The absolute stereochemistry of the tetramic acid was determined using Marfey’s method. Compounds 1 and 2 did not exhibit any significant antimicrobial or cytotoxic activity.
Levesquamide A is an isothiazolinone-containing anti-tubercular natural product isolated from Streptomyces sp. RKND-216. Through the use of Global Natural Product Social Molecular Networking (GNPS), additional members of the levesquamide family were identified (B-G). Levesquamide B is a glycosylated analogue, isolated and structurally elucidated via spectroscopical techniques along with the putative structures of levesquamide C and D. For masses relating to the additional three levesquamides (E-G), their complete structures remain ambiguous.
Natural products are a crucial source of antimicrobial agents, but reliance on low-resolution bioactivity-guided approaches has led to diminishing interest in discovery programmes. Here, we demonstrate that two in-house automated informatic platforms can be used to target classes of biologically active natural products, specifically, peptaibols. We demonstrate that mass spectrometry-based informatic approaches can be used to detect natural products with high sensitivity, identifying desired agents present in complex microbial extracts. Using our specialised software packages, we could elaborate specific branches of chemical space, uncovering new variants of trichopolyn and demonstrating a way forward in mining natural products as a valuable source of potential pharmaceutical agents.
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